Centrifugal separator

ABSTRACT

A centrifugal separator including a rotatable housing having plural, separate fluid channels therein defined between a plurality of vanes secured longitudinally within the housing. The housing has an inlet pipe at one end for admitting fluid material to be processed, and an outlet pipe at the other end for evacuating the processed material. The cross-sectional areas of the fluid channels are designed to be progressively larger toward the outlet end of the separator to facilitate separation of the material being processed. Numerous valve-controlled discharge openings are provided in the housing near the outlet end for exhausting the separated material. The discharge valves are sensitive to the specific gravity of the separated material so that they exhaust only material having a specific gravity above a predetermined level. An air vent is provided within the rotatable housing, controlled by float means, to exhaust air trapped within the housing.

United States Patent [1 1 Frewen [54] CENTRIFUGAL SEPARATOR [76] Inventor: David Frewen, 2766 Alder, Eugene,

Oreg. 97405 [22] Filed: July 29, 1970 [21] Appl. No.: 59,088

[52] US. Cl. ..233/20 R, 233/39 [51] Int. Cl. ..B04b 11/00 [58] Field of Search ..233/1 A, 20 R, 20 A, 233/21, 22, 46, 47 R, 27, 28,19 R

[56] References Cited UNITED STATES PATENTS 3,560,125 2/1971 Trump ..233/14 A 3,623,658 ll/l97l Garbaty ..233/20 R 2,067,273 l/l937 Knowles et al. ..233/28 943,083 12/1909 Kuchs .233/28 X 2,985,361 5/1961 Smith ..233/45 2,104,162 l/l938 Macklind. .233/20 R 2,353,983 7/1944 Banning ..233/46 51 May 22, 1973 Primary Examiner-George H. Krizmanich Att0rney-Kolisch and Hartwell [57] ABSTRACT A centrifugal separator including a rotatable housing having plural, separate fluid channels therein defined between a plurality of vanes secured longitudinally within the housing. The housing has an inlet pipe at one end for admitting fluid material to be processed,

and an outlet pipe at the other end for evacuating the processed material. The cross-sectional areas of the fluid channels are designed to be progressively larger toward the outlet end of the separator to facilitate separation of the material being processed. Numerous valve-controlled discharge openings are provided in the housing near the outlet end for exhausting the separated material. The discharge valves are sensitive to the specific gravity of the separated material so that they exhaust only material having a specific gravity above a predetermined level. An air vent is provided within the rotatable housing, controlled by float means, to exhaust air trapped within the housing.

8 Claims, 4 Drawing Figures CENTRIFUGAL SEPARATOR BACKGROUND OF THE INVENTION The present invention concerns a centrifugal separator for separating materials having different specific gravities. More particularly, the invention concerns a high volume centrifugal separator especially suited for removing solid pollutants from liquids.

Centrifugal separation of materials having different specific gravities is well-known. In particular, centrifuges have been widely used for separating solid or particulate materials from liquid. However, centrifugal separators have not been used generally for processing large volumes of liquid, such as would be necessary in treating sewage, for example.

Heretofore, settling tanks or settling ponds were the primary means utilized for removing solid wastes from sewage. In using such means, the sewage is directed into a large pond where the liquid is under a low velocity and the solid materials eventually settle to the bottom. The liquid is then removed from the pond by draining it from the top or pumping it out to another treatment facility. The solid waste materials are permitted to accumulate to a certain level, after which the sediment is scooped out for disposal.

It should be apparent that the use of settling tanks or ponds requires a large physical area to process high volumes of sewage. Furthermore, the ponds are open to the atmosphere and the sewage produces undesirable odors in the surrounding areas.

SUMMARY OF THE INVENTION Accordingly, it is an object of the invention to provide an improved centrifugal separator for removing particulates from liquid material.

It is another object of the invention to provide a centrifugal separator capable of handling high volumes of liquid material.

It is a further object of the invention to provide such a centrifugal separator that is especially suited for processing sewage to remove solid and particulate materials therefrom.

These and other objects of the invention are attained by a centrifugal separator that includes a housing supported for rotation about an axis passing through its opposite ends. An inlet pipe is provided at one end of the housing for admitting material to be processed, and an outlet pipe is provided at the other end for evacuating the processed material. A plurality of vanes are secured longitudinally within the housing between the ends, defining separate fluid channels extending between the inlet pipe and the outlet pipe. The cross-sectional areas of the fluid channels are designed to be progressively larger toward the outlet end of the separator to facilitate separation of the material being processed.

Discharge openings are provided in the housing near the outlet end for exhausting the separated material such as solids and particulates. The discharge openings are selectively controlled by valves that are responsive to the specific gravity of the separated materials. An air vent is provided within the rotatable housing to exhaust air trapped within the housing. The air vent is selectively opened under the control of float valve means.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevation view, in section, of a centrifugal separator designed in accordance with the invention;

FIG. 2 is a fragmentary top elevation view, in section, taken along line 2-2 in FIG. 1;

FIG. 3 is a fragmentary top elevation view, in section, taken along line 33 in FIG. 1; and

FIG. 4 is an enlarged fragmentary right elevation view taken along line 4-4 in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, a centrifugal separator 10 is generally indicated including a confining tank 11 and a housing 12 supported for rotation within the tank. about a vertical axis 13.

The tank can be fabricated of concrete, metal or other suitable structural materials and can be built above ground or set within an excavated space as shown. The tank generally includes a continuous circular sidewall 14 which can be vertical as shown or inclined outwardly to conform to the general shape of the housing. The tank further includes a cover 15 and a floor 16.

The cover is formed with a circular opening 17 in the center thereof adapted to receive a guide bearing 18. The guide bearing is of conventional design and surrounds a reinforced outlet pipe 19 which is connected to the housing, communicating between the interior of the housing and the exterior of the separator. The outlet pipe is adapted for rotation within guide bearing 18 which acts as an upper guide means establishing the axis of rotation of the housing.

A running seal, not shown, is provided between the rotating portion of the outlet pipe and a stationary por tion of pipe connected thereto for receiving the material transported through pipe 13.

Floor 16 of the tank is downwardly inclined from the center to the outer periphery thereof so that materials collected in the tank will accumulate against sidewall 14. A drain pipe 21 is provided through the sidewall at or below floor level of the tank for removing materials from the tank. A suitable pump, not shown, can be provided in the outlet drain to facilitate removal of accumulated materials.

A circular opening 22 is provided at the center of floor 16 and an enlarged equipment chamber 24 is formed beneath the floor communicating with opening 22.

A thrust bearing 27 is provided, supported on a platform 28 in chamber 24, and a guide bearing 29 is provided, secured within opening 22. Both bearings are of conventional design. A support member 30 is secured to the bottom end of the separator housing having a circular central portion 31 and a flange 32. The support member is adapted to extend downwardly from the housing through opening 22 into chamber 24. The support member is rotatable in guide bearing 29 with the flange resting upon the thrust bearing to support the housing. The outer periphery of flange 32 is provided with teeth 33 adapted to mesh with corresponding teeth on a gear 35 rotatably secured on the shaft of a motor 34. When energized, motor 34 serves to rotate the support flange and separator housing at a relatively high speed, i.e., about rpm.

A central opening, or channel, 36 is formed within the support flange and thrust bearing. An inlet pipe 25 is provided in the floor of the separator, adapted toextend through channel 36 to communicate with the interior of the separator housing. A conventional running seal 26 is provided between the wall of the inlet pipe and the inner periphery of channel 36 toprevent fluid leakage and to permit the housing to rotate freely with respect to the stationary inlet pipe.

The separator housing generally includes opposed, parallel circular end walls 37, 38 and a continuous outer sidewall 39 extending between the end walls. The upper end wall has a larger diameter than the lower end wall, and sidewall 39 diverges toward the top of the housing. Secured within the housing between the end walls are a plurality of elongate double-walled. fins or vanes 40. The double-wall construction is not necessary, but does provide a convenient way of shielding a valve control system as is explained hereinafter. The vanes are each joined along one edge to sidewall 39 and along an opposite edge to a hollow shaft 41, having closed ends, that extends through the housing along the axis of rotation. Consequently, a plurality of separate fluid channels 43 are defined between the vanes, each extending between the inlet pipe and the outlet pipe. In the embodiment described, six vanes are illustrated. However, it should be apparent that any other suitable number of vanes could be utilized to form a predetermined number of fluid channels without departing from the scope of the invention.

A liquid-free inner chamber 44 is defined in the separator housing. The chamber is generally surrounded by a circular upper plate 46, a circular lower plate 47, and a continuous inner sidewall 48 that is connected between plate 46 and plate 47. The portions of the vanes located within the fluid-free chamber can be removed, if desired, or retained to provide structural support for the separator housing. Plate 46 is of smaller diameter than plate 47 whereby wall 48 converges toward the outlet pipe. Plate 46 is formed with a generally concave surface facing the outlet pipe and plate 47 is formed with a generally concave surface facing the inlet pipe, for a purpose explained hereinafter.

In view of the divergence of wall 39 and the convergence of wall 48 toward the outlet, the fluid channels are of progressively larger cross section from the inlet end to the outlet end. The increasing cross section permits good separation of materials having different specific gravities, as the materials traverse the fluid channels under the influence of centrifugal forces caused by rotation of the housing. Due to the concave surface of plate 46, the width of each fluid channel increases between the edge of plate 46 and the outlet pipe. This serves to offset partially the constriction of the channels that results from the convergence of the vanes to the center of the housing. Therefore, the concavity of plate 46 serves to reduce turbulence in the material flowing toward the outlet pipe.

Air exhaust means are provided within the inner chamber of the separator housing, adapted for collection and removal of any air that enters the housing along with the material flowing through the inlet'pipe. The air exhaust means includes an enclosure 50 generally formed by a continuous cylindrical wall 51 closed at one end by a wall 52. The open end of the enclosure is secured around the periphery of an opening 54 formed in plate 47. Wall 52 surrounds shaft 41 and is secured thereto, as shown. A pair of tubes 56 extend in opposite directions between wall 51 and sidewall 39 of the separator housing for exhausting air from the enclosure. A wall 60 extends across enclosure 50 on the inlet side of tubes 56. Wall 60 has a plurality of perforations, or ports, 62 formed therein adapted to be selectively closed by a valve member or plate 63 secured to a float member 64. The plate and the float member each include a circular central bore 65 adapted to surround shaft 41. Thus, the float member is adapted for reciprocal movement along shaft 41 in response to the fluid level within the enclosure.

With fluid in the enclosure at a high level, the float member supports the plate in sealing engagement with perforations 62 thereby closing tubes 56. However, as air accumulates within the enclosure, the fluid level is reduced whereby the float member falls and the air is permitted to escape through the perforations and tubes 56. The concave shape of plate 47 facing the inlet pipe facilitates the collection of air that enters the housing through the inlet pipe.

As the separator housing rotates, high density materials, such as particulates, accumulate in a region along sidewall 39 at the upper end of the separator. These materials are selectively exhausted from the housing through numerous discharge ducts 66 into confining tank 14. At least one discharge duct is provided in each separate fluid channel for that purpose.

Referring now to FIGS. 3 and 4, the structure of a discharge duct is explained in detail. Each discharge duct generally comprises a short circular tube 67 extending through the outer sidewall of the housing. Each tube is normally closed by a valve 68 including a louver 69 secured to shaft 70 that is rotatably mounted in the sides of the tube. Rotation of the shaft results in movement of the louver between open and closed positions.

The louvers are adapted to occupy an open position when material above a predetermined specific gravity accumulates at the outer wall, and are adapted to occupy a closed position in the absence of such material. Accordingly, valve control means 72 are provided for each tube, being generally confined within and supported by walls 75, 76 of a housing vane. It should be apparent that the valve control means could be supported within the housing by other suitable means, however.

As shown in FIG. 3, each valve control means includes a pressure sensitive diaphragm assembly 73 secured in an opening 74 formed in wall 76 of the vane. The diaphragm assembly includes a generally circular, flexible elastomeric member 77 having a support disc 78 secured in the center thereof. A retaining ring 79 sealingly fastens the outer edge of the flexible member about the periphery of opening 74.

A linkage 80 connects support disc 78 to shaft 70 of the valve. Linkage 80 includes a link 81 pivotally connected at one end to the support disc and at the other end to a link 83. Link 83 is connected to link 81 and is fixedly connected at its other end to shaft 70. Accordingly, lateral movement of flexible member 77 serves to rotate shaft 70 and thereby move the louver between the open position shown in solid outline and the closed position shown in dotted outline in FIG. 3.

The diaphragm assembly is located in a region near the outer wall of the housing so that the outer surface of flexible member 77 is exposed to the materials which build up along the outer wall upon rotation of the housing. The inner surface of the flexible member is exposed to material of a preselected specific gravity held within a reference chamber 85.

The reference chamber includes a reservoir 86 defined between spaced-apart plugs 88, 89 within hollow shaft 41. A plurality of tubes 91 communicate with the reservoir, one tube extending through each vane to the diaphragm assembly associated with that vane. Accordingly, each tube 91 is connected at its outer end to a housing 93 that surrounds and sealingly engages the, inner surface of wall 76 around the periphery of opening 74.

A reference material of known specific gravity, such as pure water, is provided in the reservoir and tubes. An air space is provided within the reservoir to permit the diaphragm to move freely in a lateral direction.

With the housing rotating and material being processed by the separator, the lighter constituents of the material are transmitted along the fluid channels and out through the outlet pipe. The heavier constituents, such as particulates and solid matter, accumulate in a region adjacent the outer wall of the fluid channels in contact with the diaphragm assembly. As particulates of a predetermined specific gravity accumulate, the force exerted thereby upon the flexible member will overcome the opposing force of the material within the reference chamber, move the flexible member laterally and open the discharge duct. When the particulate material above the predetermined specific gravity has been exhausted, the force differential on the flexible member is eliminated so that it returns to its original position and the discharge ducts are closed. It should be apparent that a reference material of any desired specific gravity can be selected to establish a predetermined reference specific gravity for the exhausted constituents. It should also be apparent that after the specific gravity of the exhausted particulates reaches a level above the reference level, the movement of the louver in the exhaust opening is proportional to changes in the specific gravity of the exhausted materi als. This tends to clear heavy accumulations of particulates from the chamber immediately.

Once removed from the housing the exhausted constituents accumulate along the outer periphery of the floor of the confining tank and can be removed through the drain pipe for disposal.

The embodiment of the invention described herein is susceptible of construction and operation on any convenient structural scale. However, it is especially useful for early stage sewage treatment when constructed to accommodate material flow rates in the order of 100 cubic feet per second. The dimensions of the housing elements and the relative shapes of the fluid channels can be selected in accordance with known principles of fluid flow to provide satisfactory separation of 80-90 percent of the particulate material in such applications.

It is claimed and desired to secure by letters patent:

l. A centrifugal separator comprising a rotatable housing including a material inlet and a material outlet,

means in said housing defining a plurality of elongated channels therein extending between and communicating with said inlet and said outlet, and for each channel a specific gravity-responsive dis- 6 charge means sensitive to the specific gravity of material in a region of said channel and operable to discharge material in said channel from said housing on the specific gravity of material in said region exceeding a certain level, said discharge means comprising means defining a chamber adjacent said region confining fluid having a predetermined specific gravity, a comparator adjacent said chamber operable to compare the specific gravity of fluid in said chamber with that of material in said region of the channel, and valve means operatively connected to said comparator and thereby actuated to permit the discharge of material from said channel on said comparator detecting that material in said region has a specific gravity exceeding the specific gravity of the fluid in said chamber.

2. The separator of claim 1, wherein said valve means includes a closure element which is adjustable to an infinite number of different positions between a fully closed and a fully opened position, and said comparator and said closure element are interconnected through linkage means which produce an operative relationship therebetween whereby the particular intermediate position occupied at a given time by said closure element is related to the amount by which the specific gravity of material in said region of the channel exceeds the specific gravity of fluid in said chamber.

3. The separator of claim 2, wherein said comparator comprises a pressure-sensitive diaphragm.

4. A centrifugal separator comprising a rotatable housing including a material inlet and a material outlet,

means in said housing defining a channel extending between and communicating with said inlet and outlet, and

specific gravity-responsive discharge means sensitive to the specific gravity of material in a region of said channel operable to discharge material in said channel from said housing on the specific gravity of material in said region exceeding a certain level, said discharge means comprising means defining a chamber adjacent said region confining fluid having a predetermined specific gravity, a comparator adjacent said chamber operable to compare the specific gravity of fluid in said chamber with that of material in said region of the channel, and valve means operatively connected to said comparator and thereby actuated to permit the discharge of material from said channel on said comparator detecting that material in said region has a specific gravity exceeding the specific gravity of the fluid in said chamber.

5. The separator of claim 4, wherein said valve means includes a closure element which is adjustable to an infinite number of different positions between a fully closed and a fully opened position, and said comparator and said closure element are interconnected through linkage means which produces an operative relationship therebetween whereby the particular intermediate position occupied at a given time by said closure element is related to the amount by which the specific gravity of material in said region of the channel exceeds the specific gravity of fluid in said chamber.

6. The separator of claim 4, wherein said comparator comprises a pressure-sensitive diaphragm.

7. A centrifugal separator comprising a rotatable housing including an outer wall having generally opposed ends, an inlet formed in one end and an outlet formed in the other end,

termined level and to open said vent means when fluid is below said predetermined level.

8. The separator of claim 7, wherein said float valve means comprises a float which rises and falls with fluctuations in the level of fluid in said housing and means on said float operable to close off said ports when said float rises. 

3. The separator of claim 2, wherein said comparator comprises a pressure-sensitive diaphragm.
 4. A centrifugal separator comprising a rotatable housing including a material inlet and a material outlet, means in said housing defining a channel extending between and communicating with said inlet and outlet, and specific gravity-responsive discharge means sensitive to the specific gravity of material in a region of said channel operable to discharge material in said channel from said housing on the specific gravity of material in said region exceeding a certain level, said discharge means comprising means defining a chamber adjacent said region confining fluid having a predetermined specific gravity, a comparator adjacent said chamber operable to compare the specific gravity of fluid in said chamber with that of material in said region of the channel, and valve means operatively connected to said comparator and thereby actuated to permit the discharge of material from said channel on said comparator detecting that material in said region has a specific gravity exceeding the specific gravity of the fluid in said chamber.
 5. The separator of claim 4, wherein said valve means includes a closure element which is adjustable to an infinite number of different positions between a fully closed and a fully opened position, and said comparator and said closure element are interconnected through linkage means which produces an operative relationship therebetween whereby the particular intermediate position occupied at a given time by said closure element is related to the amount by which the specific gravity of material in said region of the channel exceeds the specific gravity of fluid in said chamber.
 6. The separator of claim 4, wherein said comparator comprises a pressure-sensitive diaphragm.
 7. A centrifugal separator comprising a rotatable housing including an outer wall having generally opposed ends, an inlet formed in one end and an outlet formed in the other end, bearing means supporting said housing for rotation about an axis passing through said ends, air collection means intermediate said inlet and said outlet, vent means including ports opening to said collection means for exhausting air therefrom, and float valve means operable to close off said vent means when fluid in said housing is above a predetermined level and to open said vent means when fluid is below said predetermined level.
 8. The separator of claim 7, wherein said float valve means comprises a float which rises and falls with fluctuations in the level of fluid in said housing and means on said float operable to close off said ports when said float rises. 